1. Field of the Invention
The present inventions relates to a polymerization reaction apparatus. More particularly, the present invention relates to a polymerization reaction apparatus used for producing a polymer by photo-polymerizing a polymerization precursor such as a monomer in a supercritical fluid or subcritical fluid.
Further, the present invention relates to a method of producing a polymer using this polymerization reaction apparatus.
2. Description of the Prior Art
A supercritical fluid is a fluid having a density near that of liquid and having a viscosity and diffusion coefficient near those of gas, and has a diffusion property of gas and substance dissolving property of liquid in combination, therefore, it has various effects as a reaction solvent.
Recently, there are trials for producing a polymer using a supercritical fluid, particularly, supercritical carbon dioxide, as a solvent. When supercritical carbon dioxide is used as a solvent, there is no necessity for drying and removal of a solvent after polymerization, resultantly, a process can be simplified and cost can be decreased, as compared with a solution polymerization method using an organic solvent, and the like. From the standpoint of no use of an organic solvent, load in atmospheric aspect is also small. However, carbon dioxide can be recovered and recycled easily as compared with organic solvents. Further, in many cases, since a polymer and a monomer show a difference in the degree of dissolution for carbon dioxide, the amount of unreacted monomers contained in a product polymer decreases and a polymer of higher purity can be produced, by using supercritical carbon dioxide as a solvent.
Regarding the method of producing a polymer using a supercritical fluid, for example, WO 93/20116, Japanese Patent Application Laid-Open (JP-A) Nos. 2000-26509, 2002-327003, 2001-151802, 2002-179707 and 2002-128808 disclose methods of producing a polymer in which a monomer is thermally polymerized in a supercritical fluid such as supercritical carbon dioxide. However, a method of producing a polymer in which a monomer is photo-polymerized in a supercritical fluid is not known.
On the other hand, as an apparatus used in a reaction using a supercritical fluid, Yasuhiko Arai, ed., “CHORINKAIRYUTAI NO SUBETE”, Techno System K.K., p. 586 describes an example of a circulation mode supercritical water reaction apparatus. The above-mentioned literature describes also an example of a supercritical CO2 fluid extraction apparatus with window. Conventional supercritical reaction apparatuses (supercritical fluid reaction apparatus) are all the same as the apparatus described in the above-mentioned literature.
Recently, from the standpoint of higher function and multi-function, the composition of a polymer membrane or a polymer containing a projection portion such as a polymer brush is varied, for example, along the membrane thickness direction (vertical direction against base material surface). For example, JP-A No. 2002-145971 discloses a nano structure functional body in which a graft polymer chain constituting a graft polymer layer disposed on the surface of a substrate by graft polymerization is copolymerized with a different monomer or oligomer to form a multi-layer structure containing chemical compositions varying along the membrane thickness direction.
A schematic constitution view of one example of conventional supercritical reaction action apparatuses used in photo-reaction is shown in FIG. 4. 1 represents a carbon dioxide bomb, 2 represents carbon dioxide feeding pump, 3 represents a reaction vessel capable of maintaining high temperature and high pressure conditions, 4 represents a temperature controlling means, 5 represents a window for incidence of an active energy ray (for example, quartz window), 5′ represents a window (for example, quartz window), 6 represents a light source, 7 represents a back pressure regulating valve, 9 represents a magnetic stirrer, and 10 represents a stirrer (rotor).
In the case of photo-reaction using the supercritical reaction apparatus shown in FIG. 4, first, a reaction substance (polymer precursor such as a monomer in the case of polymerization reaction) is placed in a reaction vessel 3. Next, carbon dioxide is fed from a carbon dioxide bomb 1 to the reaction vessel 3 by a pump 2. Pressure in the reaction vessel 3 is controlled by the amount of carbon dioxide to be fed, temperature in the reaction vessel 3 is controlled by a temperature controlling means 4 such as a heater, to convert carbon dioxide in the reaction vessel 3 into supercritical or subcritical condition. A photo-reaction is conducted by irradiating the inside of the reaction vessel 3 with an active energy ray through an active energy ray transmissible window 5 from a light source 6 while stirring the inside of the reaction vessel 3 by a magnetic stirrer 9 and a stirrer 10.
In the case of production of a polymer membrane or a polymer containing a projection portion such as a polymer brush, variation of the composition of a polymer to be produced along the membrane thickness direction is possible by changing the composition of a polymerization precursor to be polymerized and/or addition components to be contained in the polymer, during polymerization. It is also possible to produce polymer fine particles having a gradient composition by changing the composition of a polymerization precursor to be polymerized and/or addition components to be contained in the polymer, during polymerization. However, in the conventional supercritical reaction apparatus as shown in FIG. 4, it is not necessarily easy to change the composition of a polymerization precursor to be polymerized and/or addition components to be contained in the polymer, during polymerization.